PROJECT
UAV LiDAR surveys across nine challenging sites gave the engineering team reliable 3D terrain data for designing highway safety and resilience improvements.
Waka Kotahi NZ Transport Agency was investigating long-term resilience solutions for State Highway 6 at Granity Narrows and O’Sullivans Bluff near Murchison. To support that work, its engineering team GHD required detailed and reliable terrain information that could be used for geotechnical modelling, development and testing of design solutions, and ultimately preparation of construction contracts.
The principal technical challenge was the combination of very steep terrain, active highway, limited staging/access locations and dense vegetation.
At both sites the ground surface was heavily obscured by vegetation. This makes conventional ground survey extremely difficult and can also prevent aerial systems from reliably measuring the true ground surface if flight planning, sensor selection and processing are not carefully considered.
Projects of this nature require careful coordination of aviation requirements, traffic management, terrain, weather and operational risks while keeping safety as the overriding priority.
GHD defined the information it needed and how the information would be used. Fox Environmental then developed and managed the survey methodology.
We used an unmanned aerial vehicle (UAV) equipped with a LiDAR sensor, following carefully pre-planned flight paths to map the sites with great detail and precision. The data from these flights was processed to produce a point cloud, aerial photograph and 3D digital models of the terrain and tree canopy.
Our team managed the aviation requirements, traffic-management interface, field logistics, risk controls, data processing and quality assurance as one coordinated package. This reduced the operational burden on the client while keeping the project team informed throughout delivery.
The completed survey provided reliable 3D information for geotechnical modelling, engineering design development and contract preparation.
The result was information that GHD had confidence in and could take directly into the next stages of engineering analysis and design. The quality and usefulness of the initial Granity Narrows and O’Sullivans Bluff datasets can be seen in the expansion of the commission to include seven additional Waka Kotahi sites in the Tākaka Range / Nelson region.
If you need better spatial information to guide your decision making, get in touch today to find out how Fox Environmental can help you.
